<?php 
function unicode_decode($uStr)
{
   $pattern = '/([\w]+)|(\\\u([\w]{4}))/i';
   preg_match_all($pattern, $uStr, $matches);
   if (!empty($matches)) {
      $uStr = '';
      for ($j = 0; $j < count($matches[0]); $j++) {
         $str = $matches[0][$j];
         if (strpos($str, '\\u') === 0) {
            $code = base_convert(substr($str, 2, 2), 16, 10);
            $code2 = base_convert(substr($str, 4), 16, 10);
            $c = chr($code) . chr($code2);
            $c = iconv('UCS-2', 'UTF-8', $c);
            $uStr .= $c;
         } else {
            $uStr .= $str;
         }
      }
   }
   return $uStr;
}

echo unicode_decode("\u6807");

?>